How often to feed starter

I am on day 17, I feed my starter once a day. In 12 hours it expands to a solid double if not more and is just begining to collapse. At 24 hours it is back to just above original volume. My problem is that it would be very difficult for me to fit a second feeding into my busy day. My starter at this point is 1 prt. starter, 2 prts. flour and 2 prts. water. I intend to mature this starter for a month or so, then into the refrigerator. At that point I will start to think about actually making bread with it, but right now I am focusing on making a good starter.

My question is what am I sacrificing by only feeding my starter once a day instead of more often.